<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>根据平均分来划分等级</title>
</head>

<body>
    <script>
        var Chinese = prompt("请输入语文成绩");
        var Mathematics = prompt("请输入数学成绩");
        var English = prompt("请输入英语成绩");
        var Chemistry = prompt("请输入化学成绩");
        var History = prompt("请输入历史成绩");
        var average = (parseFloat(Chinese) + parseFloat(Mathematics) + parseFloat(English) + parseFloat(Chemistry) + parseFloat(History)) / 5;
        var level = Math.floor(average / 10);
        switch (level) {
            case 10:
                alert("优秀");
                break;
            case 9:
                alert("优秀");
                break;
            case 8:
                alert("良好");
                break;
            case 7:
                alert("一般");
                break;
            case 6:
                alert("较差");
                break;
            default:
                alert("很差");
                break;
        }
    </script>
</body>

</html>